Heretofore, fabricating a steel drum has been a laborious hit-and-miss process, which requires great skill and often days of labor to produce the pan, upper surface of the drum.
To form the pan surface a 55-gallon oil drum having a preferred quality of its steel is pounded upon its bottom end with hand or air hammers, stretching the metal into a concave bowl or dish shape. This process is known as “sinking the pan”. Care must be taken to stretch the metal evenly without deforming the rim or tearing the metal on the pan surface being formed. This process can take many hours. One advantage to forming the pan in this manner is that the hammering and working of the metal hardens it, which helps improve the timbre of the drum later on during the tuning process.
A template is used to mark the placement of each note on the sunken head of the drum. The note outlines and areas between the notes are subsequently hammered using a hand or air hammer, making the notes more visible and more importantly substantially isolating each note's vibration from the other notes in the drum. Notwithstanding, care must be taken so as to not to weaken or misform the metal during this process.
After shaping the notes an assortment of hammers are used to ‘bubble’ the notes up from beneath, which yields raised distinct surfaces on the upper side of the pan, resulting in a release of tension to prepare the notes to be hammered from the topside to align the correct pitches. Each note is effectively a steel membrane which can be played, and the finished product is numerous membranes within a drum, or more accurately numerous notes within a drum having its own fundamental, octave and harmonic pitch.
After shaping and bubbling the notes, the steel is tempered by heating and cooling the metal to increase the resilience and strength of the metal, which prepares the metal for the tuning process.
Using a stroboscope or other tuning instrument the maker hammers with a skill possessed by few, stretching and smoothing the note area so that it will vibrate precisely. Each individual note on the drumhead must be tuned in relation to the other notes, or the pan will not resonate correctly. Often a panmaker will tune each note several times before the whole pan is fully in tune.
Hand steel drums are similar to pan drums in many respects, however the upper surface of a ‘handpan’ is convex rather than concave. Thus, the bowl, which is played, is upside down so that the player plays upon a mound rather than a depression. In many ways, the handpan is much more of a precision hand percussion instrument than its predecessor the steel pan. Each note is tuned along two orthogonal axes; the first long axis produces a desired note and its octave and the other shorter axis produces that note's harmonics. Both the top and bottom surface of the handpan are bowls and is sometimes referred to as looking like a flying saucer. The top surface of the handpan has a central bass note 400 surrounded by seven or eight tonal notes 402 as is shown in FIG. 4. In a new and preferred process we have developed we use a flat die to stamp each of the tonal notes before fine tuning them through a hammering process. This stamping process provides a significant “head-start” in the tuning process. The stamping provides a planar note surface 404 and offers significant uniformity within the drums we manufacture.
One significant difference between the playing surface of a handpan drum and the pan drum, is that the handpan heretofore has been formed by stamping the metal into the required bowl or hemisphere-like shape of substantially uniform thickness, including the central bass note at the top. Although this stamping process saves a significant amount of time to produce the required spherical surface including the central bass note, we have found that the tonal quality is compromised by stamping the sheet metal. Stamping produces a hemispherical-like surface having a substantially uniform thickness across the radius of the bowl, which we believe is not preferred for all tonal fields that will reside in a mid-band region or especially the central dome note. Furthermore, stamping does not harden the metal in the same manner as hammering.
It is an objective of this invention to overcome these limitations.
This invention provides a method, which produces a drumming surface, which overcomes some of the limitations of stamping, and which does not require as many hours of hammering required to produce a traditional steel drum. Furthermore, the method produces a reproducibility and consistency not found in traditional hammering methods.
Furthermore, by stretching the metal non-uniformly and providing a varying surface thickness, so that a central region of the dome or bowl forming a ring between the central axis and the outer periphery is thinner than regions on either side of the ring, a drum surface for locating notes is provided with thickness and hardness yielding a playing surface that produces rich, vibrant, resilient and strong tones.